1. Field of the Invention
The present invention relates to a reducer including a planetary gear and a steering apparatus of a vehicle including the same, and more particularly to a reducer including a planetary gear which can compensate for a gap generated by wear of gear teeth of planet gears, sun gears, and ring gears, and a steering apparatus of a vehicle including the same.
2. Description of the Prior Art
FIG. 1 is a sectional view of a reducer using a planetary gear used in a steering apparatus of a vehicle according to the related art.
As shown in FIG. 1, the reducer using a planetary gear according to the related art includes an input shaft 110 connected to a steering shaft (not shown), a first sun gear 120 formed at a lower end of the input shaft 110, first stage planet gears 170, a second stage planet gears 180 connected to the first stage planet gears 170 by connecting shafts 175, a second sun gear 130 circumscribed about the second stage planetary gears 180, an output shaft 140 connected to the second sun gear 130, a worm wheel to which one end of the connecting shaft 175 is coupled, a worm 160 engaged with the worm wheel 150, and a carrier 190 to which an opposite end of the connecting shaft 175 is coupled.
Meanwhile, a reducer using a planetary gear constitutes, for example, an active front wheel steering apparatus of a vehicle, and a process of adjusting a ratio of an input angle and an output angle of the active front wheel steering apparatus will be briefly described below.
If a steering shaft connected to a steering wheel is rotated as a driver operates the steering wheel, an input shaft 110 connected to the steering shaft is rotated, and accordingly, a first sun gear 120 formed at a lower end of an input shaft 110 is rotated.
In this case, the first stage planet gears 170 circumscribed about the first sun gear 120 are rotated, and the second stage planet gears 180, and the second stage planet gears 180 connected to the first stage planet gears 170 by the connecting shafts 175 are rotated.
Finally, the second sun gear 130 inscribed in the second stage planet gears 180 is rotated, and accordingly, the output shaft 140 extending from the second sun gear 130 is rotated, so that a steering force generated as the driver operates the steering wheel is transferred to a rack-pinion mechanism (not shown) through the output shaft 140.
Meanwhile, if electrical signals generated by several sensors are forwarded to an ECU (not shown), the ECU drives a motor and the worm wheel 150 engaged with the worm 160 is rotated while the worm 160 connected to a motor shaft is rotated, and finally, the carrier 190 integrally formed with the worm wheel 150 is rotated such that a ration of an output angle to an input angle can be adjusted.
However, in the reducer using a planetary gear according to the related art, it is difficult to precisely control steering due to a backlash generated by wear of gear teeth, and in particular, noise generated due to a backlash of a steering apparatus of a vehicle causes an uncomfortable feeling during steering operations and noise increases as the gear teeth are worn out.